1. Field of the Invention
This invention relates to apparatus for mechanically grasping a shaft so as to prevent axial movement of the shaft with relation to the grasping apparatus, and more particularly, to means to releasably attach a knob or the like to the end of a shaft.
2. Description of the Related Art
There are numerous applications in which a knob or other device is mounted on the end of a shaft so that the device and the shaft are essentially locked together. In some instances, it is also required that the device not be able to rotate on the shaft on which the device is mounted. One such application occurs in a commonly known automotive headlight switch. The familiar operation of such a switch involves pulling the knob rearward in the vehicle and actuating the parking lights and the headlights. In addition, by rotating the knob, the vehicle's instrument lights are adjusted and the interior light is operated. Typically, the shaft rotates in synchronization with the knob to accomplish the operations.
In regard to the described type of headlight switch in a vehicle, there is occasionally a need to remove the knob from the shaft in order to remove the dashboard facia for service reasons. This need requires the knob attachment means to be removable without damage so as to be replaceable.
An existing knob anchoring means for a headlight switch comprises a formed sheet metal clip which is positioned within the knob. The clip is configured to accept the shaft and has a resilient flap which is bent by the insertion of the shaft so as to firmly grasp the shaft end. The rotational aspect of the prior art clip is accomplished by means of a non-round shaft and a mating non-round bore in the knob or in the clip (see FIGS. 1, 2A, 2B).
The existing clip described above holds the knob, but the knob is not removable when in use except by use of a special tool or by reaching beneath the dashboard to release the end of the shaft which is anchored into the switch body. An attempt to remove the knob without the special tool results in damaging and making the clip inoperable.
Another known device (FIG. 1) is used to anchor one end of a shaft used in a light switch when the opposite end of the shaft mounts to a knob used to actuate the switch functions. This anchoring device comprises an "L" shaped clip mounted on the end of a button having a captive compression spring. The shaft passes through a keyhole-shaped aperture formed in the "L" shaped clip. By pressing the button and compressing the spring, the "L" shaped clip and its aperture are moved from a position in which the "L" shaped clip lockingly engages the end of the shaft to a position in which the shaft is free to be removed. While the described device permits rotation of the shaft in the "L" shaped clip and prevents relative axial movement between the device and the shaft, both of which are advantages, the drawback to this type of shaft anchoring device is that it requires several manufacturing and assembly steps to produce and install, thus making it relatively expensive.
It is therefore an object of this invention to provide a device which can be used to assemble a knob to a shaft and prevent relative axial movement therebetween but which can be easily released to remove the knob from the shaft when necessary.
It is a further object of this invention to provide a device which can be used to assemble a knob to a shaft and prevent relative axial movement therebetween and which is both inexpensive to manufacture and to install.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.